PROJECT SUMMARY Over 600,000 inmates are released from federal and state prisons every year in the US and face the greatest risk of death related to cardiovascular disease (CVD) within the first few weeks of release. Our proposed innovation, RCPeer, is a novel mobile application system that will be designed to address the unique and pressing needs of returning citizens (RCs) as they transition back into the community. RCPeer will be designed to directly support reentry efforts led by peer specialists or peers?individuals who share characteristics with the marginalized populations they serve, such as incarceration experience. Following a community-based framework of care tailored to a disenfranchised population, RCPeer will promote RC linkage to and engagement in care by allowing the peer and RC to participate in collaborative, personalized action planning and enabling non-clinically trained peers to safely assess CVD risks using an evidence-based risk assessment tool. The unique and powerful combination of these peer-guided mobile tools will allow for the prioritization of care and linkage for those at highest risk of CVD and create an opportunity for continued conversations and personalized actions. The goal of this Phase I SBIR is to design a prototype of RCPeer and demonstrate its feasibility and acceptability with justice-involved veterans, a subpopulation of RCs with a particularly high risk of CVD. We will accomplish this goal using a user-centered design framework following three specific aims. In Aim 1, we will interview potential end users?up to 10 veteran RCs and 10 peers?and generate a user informed assessment of key aspects of the RCPeer prototype. In Aim 2, we will build and refine a working prototype using guided walkthrough interviews performed with RCs (N=5) and peers (N=5). Finally, in Aim 3, we will assess the acceptability of RCPeer through usability testing conducted with RCs (N=5) and peers (N=5). Results from Phase I will inform a potential Phase II project to evaluate the effectiveness of RCPeer on critical peer management and health outcomes, including CVD risk factors (hypertension, cholesterol), emotional well-being, quality of life, increased access to care and improvement in self-efficacy. Future work will determine how RCPeer can be further enhanced to reinforce the relationship between peers and veteran as well as non-veteran RCs they serve across a variety of program settings.